Mercury stabilizers for photographic emulsions sensitized with polyalkylene esters, amides, and ethers



United States PatentC MERCURY STABILIZERS FOR PHOTOGRAPHIC EMULSIONS SENSITIZED WITH POLYALKYL- ENE ESTERS, AMIDES, AND ETHERS Burt H. Carroll, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application April 29, 1954, Serial No. 426,544

13 Claims. (Cl. 957) This invention relates to fog inhibiting agents and stabilizers for photographic emulsions and to photographic emulsions containing them.

This application is a continuation-in-part of my ap plication Serial No. 319,614, filed November 8, 1952, now U. S. Patent 2,728,666.

It is well known that photographic emulsions on storage tend to lose sensitivity and to become spontaneously developable without exposure to light. There is normally a detectable amount of the silver salt reduced during development in the areas where no exposure was given; this is commonly called fog, and sometimes called chemical fog where it is necessary to distinguish between it and the effects of accidental exposure to radiation; in this invention, I am not concerned with the latter.

Fog depends both on the emulsion and the conditions of development; for a given emulsion it increases with the degree of development. With constant development conditions, it tends to increase with time, temperature and relative humidity of storage conditions; it is common practice to make accelerated tests of the stability of photographic emulsions by storage at increased temperature or humidity, or both. It is, of course, desirable to have emulsions as stable as possible under the conditions of high temperature and humidity which may occur in tropical climates, for example. Fog usually appears over the whole area of the sensitive coating, but when severe, it frequently is non-uniform. Fog may also be caused by exposure to chemicals, for example, hydrogen sulfide and other reactive sulfur compounds, hydrogen peroxide vapor, and strongly reducing materials. While antifoggants and stabilizers may protect, to some extent, against such effects, it is normally understood that an antifoggant protects against spontaneous growth of fog during prolonged storage or storage at high temperatures and humidities, or during development to maximum contrast and speed, or both.

It is known that the effective sensitivity of photographic silver halide emulsions may be increased by adding to them derivatives of alkylene oxides such as ethylene oxide polymers having molecular weights of 300 or more. The practical value of these compounds is severely limited by their tendency to increase fog on storage of the photographic film, especially storage at elevated temperatures and humidities. It has been found difiicult to control this by the antifoggants commonly available without using quantities of antifoggant which partly neutralize the speed increase obtained from the alkylene oxide derivatives. 7

It is therefore an object of the present invention 'to provide a method for stabilizing photographic emulsions sensitized with alkylene oxide derivatives such as polyethylene-oxides. A furtherobject is to provide ameans for reducing the fog produced upon'keeping of emulsions so sensitized, especially emulsions stored under tropical or other adverse conditions. A still further object is to provide a means for stabilizing the speed and contrast of emulsions so sensitized. Other objects will appear from the following description of my invention. These objects are accomplished by adding molecular compounds of mercuric salts with hetcrocyclic nitrogen 5 compounds, primary amine substituted heterocyclic nitrogen compounds, amine substituted mononuclear aromatic compounds, aliphatic amines containing at least 3 carbon atoms, or the halogen acid salts of any of these, to the emulsion sensitized with condensation products of alkylene oxides with aliphatic acids, aliphatic amines or phenols. Instead of molecular compounds of mercuric salts as stabilizers, I may also use organic compounds of mercury in which the mercury atom is attached by a nonionic bond to a cyclic organic nucleus and by an ionic bond to an anion (U; S. Patent 2,728,665) or simple salts of mercury with organic or inorganic acids (U. S.

Patent 2,728,664).

The alkylene oxide polymers used to sensitize the emulsions may be of various types. The alkylene oxides from which the polymers are derived contain from 2 to 4 carbon atoms, e. g., ethylene oxide, propylene oxide and butylene oxide. The preparation of polymers from these compounds is described in Ellis, The Chemistry of Synthetic Resins (1935), pages 990 to 994. These compounds are also referred to as polyalkylene glycols and their use as sensitizers for silver halide emulsions is described in U. S. Patents 2,423,549 and 2,441,389.

Condensation products of alkylene oxides with aliphatic acids, aliphatic amines and phenols, that is, polyalkylene esters, amides and ethers, are described in U. S.

Patent 1,970,578.

In each case the polyalkylene oxide or derivative of alkylene oxide should have a molecular weight of at least 300 and preferably a molecular weight of 1500 to 4000 or more.

The principal purpose of my invention is to provide a means for maintaining the sensitivity and fog of silver halide emulsions at or close to initial optimum values under keeping conditions of high temperature and humidity. Preefrably, the fog inhibitors which I propose to use are added to the emulsion at any stage during the process of manufacture prior to coating the emulsion.

The mercury fog inhibitor may be added to the emulsion in solution in any convenient solvent not injurious to the emulsion such as water, lower alcohols and ketones.

level.

Any of the mercuric compounds disclosed in Allen, Byers and Murray U. S. Patent 2,728,663 may be used to stabilize the emulsions according to my invention. The

following are typical:

HI 'HgIa \N/ NHz Bis(2-amino-5-iodopyridine hydroiodide) mercuric iodide Pyridine hydroiodide mercuric iodide 2,751,299 Patented June 19, 1956 d-nitrodimethylaniline mercuric iodide CHzSH GENE: -HCl-Hgl:

Cystein hydrochloride mercuriechloride The alkylene oxide derivatives used to sensitize the emulsions may be illustrated by the following examples, although my invention is in no way limited to the use of these specific compounds.

HOCH2CH2O (CH2CH2O nCHZCH2OCOC11H23 Polyethylene oxide- -1auric ester HQCHZCHaU (CHzCHZ )nCHzCHaNHCHzCOOH Polyethylene oxide glycine amide where n=an integer greater than about 10.

The preparation of silver halide emulsions involves three separate operations: (1) the emulsification and digestion-or ripening of the silverhalide, (2) the freeing of the emulsion from aqueous soluble salts usually by washing, (3) the second digestion or after-ripening to obtain increased sensitivity (Mees, The Theory of the Photographic Process, 1942, page 3). The fog inhibiting agents may be added at any stage, e. g., after the final digestion.

The photographic emulsions which I use are of the developing out type and best results have been obtained with gelatino-silver bromoiodide emulsions. However, emulsions of varying halide content may be used.

The emulsions may be chemically sensitized by any of-the accepted procedures, in addition to or in combination with the sensitizing with alkylene oxide polymers. The emulsions may be digested with naturally active gelatin, or sulfur compounds-may be added such as those described in Sheppard U. S. Patents 1,574,944 and 1,623,499, and Sheppard and Brigham U. S. Patent 2,410,689.

The emulsions may also be treated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium and platinum, .all of which belong to group VIII of the periodic table of elements and have an atomic weight greater than 100. Representative compounds are ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite, which are used for sensitizing in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli U. S. Patent 2,448,060, and as antifoggants in higher amounts, as described in Trivelli and Smith U. S. Patents 2,566,245 and 2,566,263.

The emulsions may also be chemically sensitized with gold salts as described in Waller and Dodd .U. S. Patent 2,399,083, Damschroder U. S. Patent 2,597,856, and Yutzy and Leermakers U. S. Patent 2,597,915. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride and 2 aurosulfobenzothiazole methochloride.

The emulsions may also be chemically sensitized with reducing agents such as stannous salts (Carroll U. S. Patent 2,487,850), polyamines such as diethylene triamine (Lowe and Jonm U. S. Patent 2,518,698), polyamines such as spermine (Lowe and Allen U. S. Patent 2,521,925), or bis-(fl-aminoethyl) sulfide and its watersoluble salts (Lowe and Jones U. S. Patent 2,521,926).

The sensitizing and stabilizing combinations of polyalkylene oxides and the mercuric compounds are effective in the presence or absence of optical sensitizing dyes. Since optical sensitizing may affect stability of emulsions with respect to sensitivity, tog and latent image changes, the action .of the compounds of this invention is not completely independent of optical sensitizing or other emulsion variables. I have found, however, that both unseusitized emulsions and emulsions sensitized with cyanineor merocyanine dyes or both may be treated with polyalkylene oxides and mercuric compounds ac cording to my invention.

The most useful concentration of the mercuric compound in the emulsion is from about 0.05 mg. to 1.0 mg. per gram mole of silver halide in the emulsion. Although higher amounts may be used, I have found that no emulsion is likely to tolerate as much as 5 times this upper limit without serious desensitization.

The stabilizing action was determined by incubation of the emulsions, usually for one week at 120 F. and constant humidity, unless otherwise stated in the examples. The results of aging tests are tabulated below and compare speed, gamma and fog of the emulsions with and without the stabilizing compound.

Example 1 One liter of a negative speed gelatino-silver bromoiodide emulsion was digested with a sulfur compound such as disclosed in Sheppard U. 5. Patent 1,574,944 and potassium chloroaurate and optically sensitized with mg. of 3,3-diethyl-9-methylthiacarbocyanine bromide per mole of silver halide. To a portion of the emulsion there was added 2 grams per gram mole of silver halide of the lauric acid ester of polyethylene oxide made by condensing 1 mole of lauric acid with approximately 26 moles of ethylene oxide. To a portion of this latter emulsion there was added 27 mg. per gram mole of silver halide of bis-(Z-amino-S-iodopyridine hydroiodide) mercuriciodi e.

The emulsions were coated on film base and were exposed on an Eastman type Ib Sensitometer and developed for 6 minutes at .68 F. in a developer of the following formula:

Grams N-methyl-p-aminophenol sulfate 1.5 Hydroquinone 1.3 Sodium sulfite (desiccated) 75 Borax -5 Potassium bromide 0.4

Water'to 1 liter The -films with and without the addenda were held at F. and constant humidity for one week and were then exposed and developed as in the case of the unincubated samples. The results of tests for speed, garnma and fog were as follows:

Example 2 Coatings were made and tested as in Example 1, using instead of the lauric ester of polyethylene oxide, one gram per gram mole of silver halide of the phenyl ether of or mixed silver halides. The mercury compounds and alkylene oxide polymers may be used in emulsions in tended for color photography, for example, emulsions containing color-forming couplers, or emulsions to be depolyethylene oxide, made by condensing one mol of 5 Veloped by Solutions containing couplersphenol with approximately 28 moles of ethylene oxide. The dlsPefslng agents y be gelatin other collold Results of tests for speed, gamma and fog were as folsuch as collodion, albumen, cellulose derivatives or synlows: thetic resins.

A t Fresh Test Alter Incubation gen Compound par mole Speed Gamma Fog Speed Gamma Fog Control 2, 850 .74 .10 1,400 .53 .16 Polyethylene oxide phenyl 1.0 g 3,800 .75 1, 950 .56 .18

ether (II). 0

g Mewmycompound 0 1 1 ,250 54 Example 3 It will be understood that I contemplate as included Coatings were made and tested as in Example 1, using instead of the lauric ester of polyethylene oxide, one gram per gram mole of silver halide of the condensation prod not of one mole of glycine with approximately moles of ethylene oxide. fog were as follows:

0 within my invention all modifications and equivalents falling within the scope of the appended claims.

What I claim is: 1. A light-sensitive silver halide emulsion sensitized Results of tests for speed, gamma and with an alkylene oxide polymer selected from the class consisting of condensation products of alkylene oxide with A t Fresh Test After Incubation gen Compound per mole 'Speed Gamma Fog Speed Gamma Fog Control 2,850 .74 .10 1,400 .53 .16 Poggthylene oxide-glycine 1.0 g 3,450 .73 .11 1,540 .55 .18

1.0g Mmuwwmpound 0 3 -1 .200 2 Example 4 aliphatic acids, condensation products of alkylene oxide Coatings were made and tested as in Example 1, using instead of the lauric ester of polyethylene oxide, one gram 0 per gram mole of silver halide of the condensation product of one mole of lauric acid amide with approximately 20 moles of ethylene oxide. Results of tests for speed, amma and fog were as follows:

with aliphatic amines, and condensation products of alkylene oxide with phenols, said alkylene oxide containing from 2 to 4 carbon atoms and said alkylene oxide polymer having a molecular weight of at least 300, said emulsion containing a small amount of a molecular addition compound of a mercuric salt with a nitrogen compound The preparation of the phenyl ether and the amides used in the above examples is more fully described in Carroll U. S. application Serial No. 426,543, filed concurrently herewith.

The polyethylene oxide polymers used in the emulsions according to my invention may be prepared either by polymerizing ethylene oxide in the presence of aliphatic acids, aliphatic amines or phenols, or by reacting the polymerized polyethylene oxide with aliphatic acids, acid chlorides, or esters, which produces similar products.

Instead of incorporation in the silver halide emulsion the fog-inhibitors of my invention may be incorporated in a colloid layer such as a gelatin layer in contact with the emulsion.

The fog-inhibiting agents which I have described may be used in various kinds of photographic emulsions. In addition to being useful in ordinary non-sensitized emulsions they may also be used in orthochromatic, panchromatic and X-ray emulsions. If used with sensitizing dyes, they may be added to the emulsion before or after the dyes are added. Various silver salts may be used as the sensitive salt, such as silver bromide, silver iodide, silver chloride selected from the class consisting of heterocyclic nitrogen compounds in which at least three bonds of the heterocyclic nitrogen atom are attached to carbon, amine-substituted mononuclear aromatic compounds in which three bonds of the amino nitrogen atom are attached to carbon, and their halogen acid salts, and the halogen acid salts of aliphatic amines containing at least three carbon atoms.

2. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation product of one mol of lauric acid with approximately 26 moles of ethylene oxide, said emulsion containing a small amount of a bis-(2-amino-5-iodopyridine)hydroiodide mercuric halide.

3. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation product of one mol of glycine with approximately 20 moles of ethylene oxide, said emulsion containing a small amount of a bis-(2-amino-5-iodopyridine)hydroiodide mercuric halide.

4. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation product of .one mol of lauryl amide -with.,approximately 20 n uzgles of ethylene oxide, said emulsion containing a small amount of a bis-(2-amino-5-iod0pyridine)hydroiodide mercuric halide.

5. A light-sensitive silver halide emulsion sensitized with an ethylene oxide polymer which is a condensation product of one mol of phenolwith approximately 28 moles of ethylene oxide, said emulsion containing a small amount of a bis-(2-amino-5-iodopyridine)-hydroiodide mercuric halide.

6. A light-sensitive sulfur-sensitized silver halide emulsion additionally sensitized with an ethylene oxide polymer selected from the class consisting of condensation products of ethylene oxide with aliphatic acids, condensation products of ethylene oxide with aliphatic amines and condensation products of ethylene oxide with phenols, said ethylene oxide polymer having a molecular Weight of at least 300, said emulsion containing a small amount of a molecular addition compound of a mercuric salt with a nitrogen compoundselected from the class consisting of heterocyclic nitrogen compounds, primary amine substituted heterocyclic nitrogen compounds in which at least three bonds of the heterocyclic nitrogen atom are attached to carbon, amine-substituted mononuclear aromatic compounds in which three bonds-of theamino nitrogen atom are attached to carbon, and their halogen acid salts, and the halogen, acid salts of aliphatic amines containing at least three carbon atoms.

7. A light-sensitive sulfur-sensitized silver halide emulsion additionally sensitized with an ethylene oxide polymer which is a condensation product of one mol of lauric acid with approximately 26 moles of ethylene oxide, said emulsion containing a small amount of bis-(Z-amino-S- iodopyridine hydroiodide) mercuric iodide.

8. A light-sensitive sulfur-sensitized silver halide emulsion additionally sensitized with an ethylene oxide polymer which is a condensation product of one mol of glycine with approximately 20 moles of ethylene oxide, said emulsion containing a small amount of bis-(Z-amino-S- iodopyridine hydroiodide) mercuric iodide.

9. A light-sensitive sulfur-sensitized gelatino-silver halide emulsion additionally sensitized with an ethylene oxide polymer which is a condensation product of one mol of lauryl amide with approximately 20 moles of ethylene oxide, said emulsion containing a small amount of bis-(Z-amino-S-iodopyridine hydroiodide) mercuric iodide.

10. A light-sensitive sulfur-sensitized gelatino-silver halide emulsion additionally sensitized with an ethylene oxide polymer which is a condensation product of one mol of phenol with approximately 28 moles of ethylene oxide, said emulsion containing a small amount of his- (2-amino-5-iodopyridine hydroiodide) mercuric iodide.

11. The emulsion of claim 7 which is additionally chemically sensitized with gold salts.

12. The emulsion of claim 8 which is additionally chemically sensitized with gold salts.

13. The emulsion of claim 9 which is additionally chemically sensitized with gold salts.

References Cited in the file of this patent UNITED STATES PATENTS 1,574,944 Sheppard Mar. 2, 1926 1,738,530 Frankenburger et al. Dec. 10, 1929 2,423,549 Blake et al. July 8, 1947 FOREIGN PATENTS 633,159 Great Britain Dec. 12, 1949 

1. A LIGHT-SENSITIVE SILVER HALIDE EMULSION SENSITIZED WITH AN ALKYLENE OXIDE POLYMER SELECTED FROM THE CLASS CONSISTING OF CONDENSATION PRODUCTS OF ALKYLENE OXIDE WITH ALIPHATIC ACIDS, CONDENSATION PRODUCTS OF ALKYLENE OXIDE WITH ALIPHATIC AMINES, AND CONDENSATION PRODUCTS OF ALKYLENE OXIDE WITH PHENOLS, SAID ALKYLENE OXIDE CONTAINING FROM 2 TO 4 CARBON ATOMS AND SAID ALKYLENE OXIDE POLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST 300, SAID EMULSION CONTAINING A SMALL AMOUNT OF A MOLECULAR ADDITION COMPOUND OF A MERCURIC SALT WITH A NITROGEN COMPOUND SELECTED FROM THE CLASS CONSISTING OR HETEROCYCLIC NITROGEN COMPOUNDS IN WHICH AT LEAST THREE BONDS OF THE HETEROCYCLIC NITROGEN ATOM ARE ATTACHED TO CARBON, AMINE-SUBSTITUTED MONONUCLEAR AROMATIC COMPOUNDS IN WHICH THREE BONDS OF THE AMINO NITROGEN ATOM ARE ATTACHED TO CARBON, AND THEIR HALOGEN ACID SALTS, AND THE HALOGEN ACID SALTS OF ALIPHATIC AMINES CONTAINING AT LEAST THREE CARBON ATOMS. 